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Medscape Gastroenterology
MEDLINE Abstracts
Functional Gastrointestinal Disorders:
Approach to Management
What's new concerning the management of functional
gastrointestinal disorders? Find out in this easy-to-navigate
collection of recent MEDLINE abstracts compiled by the editors at
Medscape Gastroenterology. [Medscape Gastroenterology, 1999.
(C) 1999 Medscape, Inc.]
Review Article: Clinical Evidence to Support
Current Therapies of Irritable Bowel Syndrome
Camilleri M
Aliment Pharmacol Ther 13(Suppl 2):48-53, 1999 May
This review summarizes the clinical evidence to support current therapies in
irritable bowel syndrome (IBS). Fibre is indicated at a dose of at least 12 g
per day in patients with constipation-predominant IBS. Loperamide (and probably
other opioid agonists) are of proven benefit in diarrhoea-predominant IBS; loperamide may also aid continence by enhancing resting anal tone.
In general, smooth muscle relaxants are best used sparingly, on an 'as needed'
basis, as their overall efficacy is unclear. Psychotropic agents are important
in relieving depression and of proven benefit for pain and diarrhoea in patients with depression associated with IBS.
Further trials with selective serotonin reuptake inhibitors (SSRIs) are awaited.
Psychological treatments including hypnotherapy are less widely available, but
may play an important role in relief of pain. In summary, current therapies targeted on the predominant symptoms in IBS are
moderately successful. New therapies are needed to more effectively relieve this
syndrome, not just symptoms.
Review Article: An Integrated Approach to the
Irritable Bowel Syndrome
Drossman DA
Aliment Pharmacol Ther 13(Suppl 2):3-14, 1999 May
Our understanding of the pathophysiology of irritable bowel syndrome (IBS) has
evolved from a disorder of motility to a more integrated understanding of
enhanced motility and visceral hypersensitivity associated with brain-gut
dysfunction. Psychosocial factors contribute to the predisposition,
precipitation and perpetuation of IBS symptoms, and affect the clinical outcome.
Newer brain imaging techniques (e.g. PET, fMRI) may help us understand the
relationship between altered emotional states with pain enhancement and other
gastrointestinal symptoms. Diagnosis
using symptom-based (e.g. Rome) criteria and a conservative diagnostic approach
is recommended. Treatment is based on an effective physician-patient
relationship and a combined pharmacological and behavioural approach. Newer
medications acting at the 5-HT receptor may help in reducing pain and bowel
dysfunction. For more severe pain, antidepressants may be considered.
The Effects of Biofeedback on Rectal Sensation and
Distal Colonic Motility in Patients With Disorders of
Rectal Evacuation: Evidence of an Inhibitory
Rectocolonic Reflex in Humans?
Mollen RM, Salvioli B, Camilleri M, Burton D, Kost LJ,
Phillips SF, Pemberton JH
Am J Gastroenterol 94(3):751-6, 1999 Mar
Objective: Abnormalities of descending colon motility reported in a subset of
patients with rectal evacuation disorders are consistent with a rectocolonic
inhibitory reflex. Our aims were to evaluate distal colon motor function and rectal sensation in such patients and assess
effects of biofeedback (BF) training on these functions.
Methods: Seven patients (five women, two men; mean age 36 yr) with rectal
evacuation disorders were studied before and after 10-days biofeedback training;
six healthy volunteers (five women, one man; mean age 30 yr) were studied once.
Colonic compliance, motility, sensation thresholds, and perception scores during
standardized rectal distentions were measured using two barostat-manometry
assemblies inserted into the cleansed colon with the aid of flexible
sigmoidoscopy.
Results: Sigmoid compliance, fasting, and postprandial motility index, and
perception thresholds were similar in controls and patients before and after
biofeedback training. Postprandial sigmoid tone tended (p = 0.09) to be lower in
patients than controls; after biofeedback, postprandial tone was comparable to
that in controls.
Rectal urgency scores at 24 mm Hg distention were greater in patients than in
controls (p = 0.02 for both). After biofeedback, there were trends for lower
perceptions of urgency to defecate (7.6 +/- 1.1 cm pre- vs 5.3 +/- 1.5 post-; p
= 0.04) at 24 mm Hg; conversely, gas sensation at 12 mm Hg was higher (1.2 +/-
0.5 cm pre- vs 3.3 +/- 0.6 post-; p = 0.05).
Conclusions: Normalization of rectal evacuation and postprandial sigmoid tone in
patients with evacuation disorders by biofeedback training supports the presence
of a rectocolonic inhibitory reflex.
Effect of biofeedback on rectal sensation in these patients requires further
study.
Motor Function in Irritable Bowel Syndrome
Camilleri M
Can J Gastroenterol 13(Suppl A):8A-11A, 1999 Mar
The evidence supporting a role of abnormal motor function in irritable bowel
syndrome (IBS) is reviewed. Symptoms commonly present in IBS patients, such as
vomiting, diarrhea, constipation or incomplete rectal evacuation, indicate that
a motor disorder is implicit as either a primary or secondary disturbance.
Physiological studies implicate a disturbance of transit through the small bowel
and proximal colon, and abnormal motor responses of the rectum to distention in
IBS patients. Intestinal contractions (physiological or 'abnormal') are
associated with the sensation of pain, suggesting that these contractions are
interactions between abnormal motor and sensory functions in IBS. Therapies
aimed at correcting abnormal transit or antispasmodics are the main
pharmacological approaches to the relief of IBS, and, although the latter are
not always effective in the long term response to treatment, they support the
role of dysmotility in IBS. Most novel therapies under trial probably modulate
both sensory and motor functions, and are discussed briefly. In summary, the
weight of clinical, physiological and pharmacological evidence supports a role
of abnormal motility in IBS.
Recommendations for the Management of Irritable
Bowel Syndrome in Family Practice. IBS Consensus
Conference Participants.
Paterson WG, Thompson WG, Vanner SJ, Faloon TR, Rosser
WW, Birtwhistle RW, Morse JL, Touzel TA
CMAJ 161(2):154-60, 1999 Jul 27
To help family physicians manage patients with irritable bowel syndrome (IBS), a
consensus conference was convened in June 1997 at which 5 internationally
recognized experts in IBS presented position papers on selected topics
previously circulated to the conference participants. Five working groups
comprising family physicians, gastroenterologists and allied health care
professionals from across Canada were then charged with developing
recommendations for the diagnosis, patient education, psychosocial management,
dietary advice and pharmacotherapy, respectively. An evidence-based approach was
used where possible; otherwise, recommendations were made by consensus. The
participants concluded that family physicians can make a positive diagnosis of
IBS using symptom criteria. The pathophysiology is poorly understood, but
motility and sensory disturbances appear to play a role. Neither psychological
nor specific dietary factors cause IBS, but both can trigger symptoms. Drug
therapy is not recommended for the routine treatment of IBS, but short-term
trials of drug therapy may be targeted to predominant symptoms in selected patients. A step-wise,
patient-centred approach to management is outlined.
Functional Colonic Diseases: From Physiopathology
to Pharmacology
Bardou M
Rev Med Interne 20(2):151-7, 1999 Feb
Introduction: Irritable bowel syndrome is a very frequent cause for consulting.
The clinical entity is ill-defined and diagnosis is based on clinical features (Rome
criteria), as no specific feature helps guide the diagnosis. Since its pathophysiology is currently being better described,
this study was aimed at reviewing recent data.
Current Knowledge And Key Points: After involvement of the motor system had been
suggested, more recent pathophysiological studies have focused on diffuse
abnormalities of visceral perception with decrease in pain thresholds.
Involvement of other physiopathological factors, particularly of psychological
disturbances, has been suggested.
Future Prospect And Projects: Management of patients suffering from irritable
bowel syndrome is still disappointing as pharmacological agent acting on gut
motility are only partly efficacious. Better understanding of its
physiopathology will open new avenues for the development of therapeutical
agents truly efficacious on visceral hypersensitivity.
Management of Irritable Bowel Syndrome: Novel
Approaches to the Pharmacology of Gut Motility
Scarpignato C, Pelosini I
Can J Gastroenterol 13(Suppl A):50A-65A, 1999 Mar
Although it is unclear to what extent irritable bowel syndrome (IBS) symptoms
represent a normal perception of abnormal function or an abnormal perception of
normal function, many believe that IBS constitutes the clinical expression of an underlying motility disorder,
affecting primarily the mid- and lower gut. Indeed, transit and contractile
abnormalities have been demonstrated with sophisticated techniques in a subset
of patients with IBS. As a consequence, drugs affecting gastrointestinal (GI)
motility have been widely employed with the aim of correcting the major IBS
manifestations, ie, pain and altered bowel function. Unfortunately, no single
drug has proven to be effective in treating IBS symptom complex. In addition,
the use of some medications has often been associated with unpleasant side
effects. Therefore, the search for a truly effective and safe drug to control
motility disturbances in IBS continues. Several classes of drugs look promising and are under evaluation.
Among the motor-inhibiting drugs, gut selective muscarinic antagonists (such as
zamifenacin and darifenacin,neurokinin2 antagonists (such as MEN-10627 and MEN-11420), beta3-adrenoreceptor
agonists (eg, SR-58611A) and GI-selective calcium channel blockers (eg,
pinaverium bromide and octylonium)are able to decrease painful contractile activity in the gut (antispasmodic
effect), without significantly affecting other body functions. Novel mechanisms
to stimulate GI motility and transit include blockade of cholecystokinin (CCK)A
receptors and stimulation of motilin receptors. Loxiglumide (and its
dextroisomer, dexloxiglumide) is the only CCKA receptor antagonist that is being
evaluated clinically. This drug accelerates gastric emptying and colonic transit,
thereby increasing the number of bowel movements in patients with chronic
constipation. It is also able to reduce visceral perception. Erythromycin and
related 14-member macrolide compounds inhibit the binding of motilin to its
receptors on GI smooth muscle and, therefore, act as motilin agonists. This
antibiotic accelerates gastric emptying and shortens orocecal transit time. In
the large bowel a significant decrease in transit is observed only in the right colon, which suggests a shift in fecal distribution. Several 'motilinomimetics'
have been synthesized. Their development depends on the lack of antimicrobial
activity and the absence of fading of the prokinetic effect during prolonged administration.
5-hydroxytryptamine (5-HT)4 agonists with significant pharmacological effects on
the mid- and distal gut (such as prucalopride and tegaserod) are available for
human use. These 'enterokinetic' compounds are useful for treating constipation-predominant IBS patients. 5-HT3 receptor antagonists also possess a
number of interesting pharmacological properties that may make them suitable for
treatment of IBS. Besides decreasing colonic sensitivity to distension, these
drugs prolong intestinal transit and may be particularly useful in
diarrhea-predominant IBS.
Finally, when administered in small pulsed doses, octreotide, besides reducing
the perception of rectal distension, accelerates intestinal transit, although
other evidence disputes such an effect.
CONTENTS
Review Article: Clinical
Evidence to Support Current
Therapies of Irritable Bowel
Syndrome
Review Article: An Integrated
Approach to the Irritable Bowel
Syndrome
The Effects of Biofeedback on
Rectal Sensation and Distal
Colonic Motility in Patients
With Disorders of Rectal
Evacuation: Evidence of an
Inhibitory Rectocolonic Reflex
in Humans?
Motor Function in Irritable
Bowel Syndrome
Recommendations for the
Management of Irritable Bowel
Syndrome in Family Practice.
IBS Consensus Conference
Participants
Functional Colonic Diseases:
From Physiopathology to
Pharmacology
Management of Irritable Bowel
Syndrome: Novel Approaches
to the Pharmacology of Gut
Motility
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